172-4 Assessing the Environmental Impacts of Historical Iron Smelting in the Shenandoah Valley of Virginia

Session: Environmental Geochemistry and Health (Part II)

Presenting Author:

Kylie Sheridan

Authors:

Sheridan, Kylie Bree¹, Hinkle, Margaret Anne G², Uffelman, Erich S.³

(1) Earth and Environmental Geoscience, Washington and Lee University, Lexington, Virginia, USA; Earth and Environmental Sciences, University of Missouri - Kansas City, Kansas City, Missouri, USA, (2) Earth and Environmental Geoscience, Washington and Lee University, Lexington, Virginia, USA, (3) Department of Chemistry and Biochemistry, Washington and Lee University, Lexington, Virginia, USA,

Abstract:

Centuries of iron smelting in Virginia have left a persistent environmental legacy in the form of widespread slag deposits. This study characterizes the geochemical composition of these slags and assesses the environmental risk they may pose to surrounding ecosystems at three study sites in the Shenandoah Valley of Virginia, with differing proximity to nearby communities: Glenwood Furnace, Roaring Run Furnace, and Grace Furnace. At each site, samples of slag, ash, iron ore, soil, and stream water (where applicable) were collected and analyzed. Additionally, to study the mobility of metals from the slag into the surrounding systems, a leaching experiment was conducted reacting select slag with synthetic rainwater at initial pH of 4.2 and 5.3 to mimic pre- and post-1994 Eastern United States rainwater, respectively. The principal results show that the surrounding topsoils are particularly elevated in Mn, Ti, and Pb when compared to national reference soils, with Roaring Run, Grace, and Glenwood furnaces containing on average 500 ± 200, 400 ± 200, and 120 ± 40 ppm Pb, respectively. Slag are compositionally dominated by Ca, Fe, and Mn, with lesser concentrations of Ti, K, Pb, and Sr, and trace concentrations of Ni and Cu. Surface water analyses revealed the main contaminants of interest (Pb, Cr, Ti, and Mn) are well below safe drinking water levels. The leaching experiments similarly revealed potential contaminants of interest remain low in solution after reacting slag for 18 hours, with the exception of Mn. Substantial Ca, K, and Si leach from the slag into solution, and the pH of the synthetic rainwater increases substantially from initial values of 4.2 and 5.3 to over 10. Thus, these results suggest the elevated contaminant concentrations in slag-impacted soils may be due to leaching from the slag followed by rapid reprecipitation due to increased pH, or via the retention of fine grain (10-50 μm) slag particles within topsoil and limited leaching of contaminants. In both cases, soil contamination is increased while surface water contamination is limited. Based on the metal concentrations in the soils and within the slags themselves, these results also indicate that Glenwood Furnace, the site that is nearest to a community, poses the lowest environmental risk. 

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